Foreign and domestic automobile manufacturers have put hybrid vehicles (hereinafter abbreviated as HEV) to practical use as measures against environmental problems such as global warming. Currently, HEVs are also diversified into large-sized vehicles, recreational vehicles and the like. Development of electric vehicles (hereinafter abbreviated as EV) is also active. HEVs and EVs require a great motor output and a high-capacity battery is mounted thereon.
Therefore, in order to drive HEVs and EVs stably and efficiently, a high-performance high-capacity relay is essential. A vehicle-mounted high-capacity relay is attached to a limited space, and thus, a reduction in size and weight is required. In addition, in order to improve the energization performance of the relay, it is necessary to suppress an increase in temperature during continuous energization as much as possible, while using a low-resistance metal in an energized portion. Furthermore, because of a vehicle-mounted component, the high-capacity relay also requires robustness and reliability to withstand severe vibrations and temperature load (refer to NPD 1).
An example of such a high-capacity relay is an electromagnetic relay described in Japanese Patent Laying-Open No. 2015-046377 (PTD 1). This electromagnetic relay includes an electromagnet device, a contact device and a trip device.
The electromagnet device has a first exciting coil, a movable element and a first stator. The electromagnet device attracts the movable element to the first stator by a magnetic flux generated when the first exciting coil is energized, and moves the movable element from a second position to a first position.
The contact device has a fixed contact and a movable contact. The movable contact moves with the movement of the movable element, and thus, a closed state in which the movable contact is in contact with the fixed contact is formed when the movable element is located in the first position, and an open state in which the movable contact is away from the fixed contact is formed when the movable element is located in the second position and in a third position.
The trip device has a second exciting coil connected in series to the contact device. The trip device moves the movable element to the third position by a magnetic flux generated by the second exciting coil when an abnormal current of not less than a prescribed value flows through the contact device in a state in which the movable element is located in the first position.
The contact device, the electromagnet device and the trip device are aligned in one direction. The trip device is disposed on the side opposite to the contact device with respect to the electromagnet device.
As such a contact device forming a vehicle-mounted high-capacity relay, a contact device in which a space having a fixed contact and a movable contact arranged therein is a hermetic space and the space is filled with an arc-extinguishing gas (insulating gas) has been conventionally used in order to quickly extinguish an arc generated when the contacts are opened.
For example, in a contact device described in Japanese Patent Laying-Open No. 2015-049939 (PTD 2), a housing, a coupling body, a plate, and a plunger cap are hermetically joined to form a hermetic space that houses a fixed contact and a movable contact. In the contact device, a space surrounded by the housing, the coupling body, the plate, and the plunger cap is the hermetic space and an arc-extinguishing gas mainly composed of hydrogen is injected into this hermetic space.